Import please insted of convert
I've imported many JPG files into CD12. After importing them, they become bitmaps and are only editable using tools like those used in CorelPaint, Photoshop, etc. If you import a JPG that has text, you cannot select or edit that text.
If you have Paint or Photoshop, what you can do is paint over the text with the text's background color and then insert some other text in its place. I've done that when I download a greeting card from the internet and then change its text to whatever I want.
I suppose I could also do something similar using CorelDraw but I always use Photoshop to remove the text. After that, I could then import the JPG into CD and then add new text to it, but I usually just use Photoshop to add the text.
Hope this helps!